The present invention relates to a composition which conceals grazes or scratches on glass surfaces such as repeatedly reusable glass bottles. More particularly, the present invention relates to a composition which may be characterized as a film formed by coating an emulsion obtained by mixing a composition whose principal ingredient is a polydiorganosiloxane capable of forming an adhesive film on a glass surface at room temperature and a composition whose principal ingredient is a polydiorganosiloxane fluid.
Glass bottles used as containers for beer, soft drinks and milk are usually collected after use and repeatedly reused. On the surface of such glass bottles, grazes are caused by the bottles contacting one another or contacting metals such as in machines utilized in the packing process or distribution. As the appearance of the bottles becomes less attractive by repeated reuse, the value of the packaged goods also apparently becomes lower.
To prevent the degradation of the appearance of the glass bottles several proposals have been made to form a graze-proof film or to form a concealing film for grazes. However, a satisfactory material has not been found because a variety of properties are necessary to form such graze-proof agents or concealing agents. Some properties which must be present simultaneously include:
(1) PA0 (2) Good water resistance and no oil film formed on water when the coated bottle is dipped into water. PA0 (3) No change in the appearance of the bottle; no stickiness and no unusual lubricity due to the presence of the coating film. PA0 (4) Easy handling. PA0 (5) PA0 (6) Safe for contact with the human body or foods. PA0 (7) No odor. PA0 (1) expensive ethanol is required as the solvent, and PA0 (2) such as low molecular weight polyorganosiloxane resin results in a film having insufficient film strength and adhesiveness to glass so that the film formed falls off irregularly during the bottle washing process and thus causes a poorer appearance than an uncoated bottle. PA0 (1) it is highly flammable and toxic due to the use of solvent; PA0 (2) the film formed falls off irregularly during the bottle washing process; and, PA0 (3) the film becomes yellowish upon storage because of the large number of amino group-containing organic groups which are necessary. PA0 (1) 0.1-60 weight percent based on composition (A) of the reaction product of: PA0 (2) 1-50 weight percent based on composition (A) of a compound of the formula: EQU [R.sup.7 R.sup.8 SiO].sub.n PA0 wherein R.sup.7 and R.sup.8 are the same or different substituted or unsubstituted hydrocarbon radicals having 1-50 carbon atoms and n is an integer equal to 3-6 inclusive; PA0 (3) 0.1-20 weight percent based on composition (A) of a cationic surfactant or a surfactant mixture in which a part of the cationic surfactant is replaced with a nonionic surfactant; PA0 (4) 20-90 weight percent based on composition (A) of water; and PA0 (5) an effective amount of an alkali metal hydroxide having catalytic ability. PA0 (1) 0.1-60 weight percent based on composition (A) of the reaction product of: PA0 (2) 1-50 weight percent based on composition (A) of a compound of the formula: EQU [R.sup.7 R.sup.8 SiO].sub.n ( 3) PA0 wherein R.sup.7 and R.sup.8 are the same or different substituted or unsubstituted hydrocarbon radicals having 1-50 carbon atoms and n is an integer equal to 3-6 inclusive; PA0 (3) 0.1-20 weight percent based on composition (A) of a cationic surfactant or a surfactant mixture in which part of the cationic surfactant is replaced with a nonionic surfactant; PA0 (4) 20-90 weight percent based on composition (A) of water; and PA0 (5) an effective amount of an alkali metal hydroxide having catalytic ability.
(a) For a graze-proof film: Excellent film stability under grazing conditions. PA1 (b) For a concealing film: Excellent concealing property for graze. PA1 (a) Perfect removability by a bottle washing process utilizing an alkaline water, or PA1 (b) resistance to a bottle washing process and no hindrance to the labeling or other process. PA1 (a) 0.1-50 weight percent based on the total of (a) and (b) of the product obtained by reacting: PA1 (b) 50-99.9 weight percent based on the total of (a) and (b) of a polydiorganosiloxane having at least one silanol group in the molecule and a viscosity at 25.degree. C. of 5-10,000 cSt; PA1 (a) 0.1-50 weight percent based on the total of (a) and (b) of the product obtained by reacting: PA1 (b) 50-99.9 weight percent based on the total of (a) and (b) of a polydiorganosiloxane having at least one silanol group in the molecule and a viscosity at 25.degree. C. of 5-10,000 cSt;
Japanese patent application No. 56040/1980, Kokai, which corresponds to U.S. Pat. No. 4,273,834, proposed such a concealing agent formed from a polyorganosiloxane resin containing methyl, phenyl and alkoxy groups bonded to silicon atoms. This concealing agent, however, is dissolved at a higher molecular weight stage only by hydrocarbon solvents such as toluene, xylene or gasoline. Therefore, it is not suitable for application to food containers from a hygiene standpoint. When the concealing agent is made to a low molecular weight the polyorganosiloxane can be dissolved in ethanol so the foregoing problem is avoided, but there are still two disadvantages:
An adhesive coating material in which the principal ingredient is polyorganosiloxane having siloxane units containing an amino group-containing organic group bonded to the silicon atom to improve adhesiveness is described by Japanese publication No. 3627/1971, (which corresponds to U.S. Pat. No. 3,574,673) as a metal surface leveling agent. This coating material, however, has several disadvantages for purposes of the present invention:
Several latexes and emulsions of polyorganosiloxanes having functionality such as an amino group-containing group, a mercapto group-containing group and/or a trialkoxysilyl group to give an adhesiveness or form a crosslinked structure is proposed as a treatment agent for fibers and the like in Japanese patent application No. 131661/1979, Kokai which corresponds, to U.S. Pat. No. 4,228,054. However, when such a latex or emulsion is used for coating glass bottles, because its main component is a crosslinkable polyorganosiloxane, the film formed from the latex or emulsion falls off irregularly or the surface of the film becomes roughened by the bottle washing process. Additionally, when a tin compound is used as a catalyst, there is the disadvantage of toxicity.
The present inventors made investigations to discover a concealing agent for grazes or scratches on glass bottles and found that by using a composition obtained by making an emulsion from a composition whose principal ingredient is a polysiloxane capable of forming an adhesive film on glass surfaces at room temperature and a composition whose principal ingredient is a polyorganosiloxane fluid, a film can be formed which is totally removable by the bottle washing process. The present invention has been completed on the basis of these findings.